The present invention relates generally to annuloplasty prostheses and methods for repair of heart valves. More particularly, it relates to annuloplasty rings, and related instruments and procedures, for reconstructing and remodeling a valve annulus of a patient's heart, for example a mitral valve annulus.
Heart valves, such as the mitral, tricuspid, aortic, and pulmonary valves, are sometimes damaged by disease or by aging, resulting in problems with the proper functioning of the valve. Heart valve problems generally take one of two forms: stenosis, in which a valve does not open completely or the opening is too small, resulting in restricted blood flow; or insufficiency or regurgitation, in which blood leaks backward across a valve that should be closed.
Annuloplasty prostheses, generally categorized as either annuloplasty rings or annuloplasty bands, are employed in conjunction with valvular reconstructive surgery to assist in the correction of heart valve defects such as stenosis and valvular insufficiency. There are two atrio-ventricular valves in the heart. The mitral valve is located on the left side of the heart, and the tricuspid valve is located on the right side. Anatomically speaking, each valve type forms or defines a valve annulus and valve leaflets.
Both valves can be subjected to or incur damage that requires the valve in question be repaired or replaced. The effects of valvular dysfunction vary. For example, mitral regurgitation, a complication of end-stage cardiomyopathy, has more severe physiological consequences to the patient as compared to lone tricuspid valve regurgitation. Regardless, many of the defects are associated with dilation of the valve annulus. This dilation not only prevents competence of the valve, but also results in distortion of the normal shape of the valve orifice. Remodeling of the annulus is therefore central to most reconstructive procedures on the mitral and tricuspid valves. In this regard, clinical experience has shown that repair of the valve, when technically possible, produces better long-term results as compared to valve replacement.
Many procedures have been described to correct the pathology of the valve leaflets and their associated chordae tendinae and papillary muscles. For example, with respect to the mitral valve, two leaflets are present, the anterior leaflet and the posterior leaflet, such that the mitral valve annulus is commonly described as having an anterior aspect and a posterior aspect. With this in mind, in mitral repairs, it is considered important to preserve the normal distance between the two fibrous trigones. The trigones essentially straddle the anterior aspect of the annulus. A significant surgical diminution of the inter-trigonal distance may cause left ventricular outflow obstruction. Thus, it is desirable to maintain the natural inter-trigonal distance during and following mitral valve repair surgery.
Consequently, when a mitral valve is repaired, the result is generally a reduction of the size of the posterior aspect of the mitral valve annulus. As part of the mitral valve repair, the involved segment of the annulus is diminished (i.e., constricted) so that the leaflets may coapt correctly on closing, or the annulus is stabilized to prevent post-operative dilation from occurring, either as frequently achieved by implantation of a prosthetic ring or band at the level of the valve annulus in the atrium. The purpose of the ring or band is to restrict and/or support the annulus to correct and/or prevent the valvular insufficiency. However, it is important not to overly restrict the annulus as an unacceptable valvular stenosis or Systolic Anterior Motion (SAM) of the anterior leaflet may result. In tricuspid valve repair, constriction of the annulus usually takes place in a posterior leaflet segment and in a small portion of the adjacent anterior leaflet. The septal leaflet segment is not usually required to be shortened.
Previously, valve repair or replacement required open-heart surgery with its attendant risks, expense, and extended recovery time. Open-heart surgery also requires cardiopulmonary bypass with risk of thrombosis, stroke, and infarction. More recently, flexible valve prostheses and various delivery devices have been developed so that replacement valves can be implanted transvenously using minimally invasive techniques.